"We're arguing for much more focus on biodiversity conservation right across what governments are doing," says Kingsford.

Oceania covers Australia, Melanesia, Micronesia, New Zealand and Polynesia and contains six of the world's 39 biodiversity hotspots, say the researchers, who reviewed evidence from 24,000 publications.

They say invasive plants and animals have devastated terrestrial species in the Pacific Island and caused 75% of all terrestrial vertebrate extinctions, including the extinction of 1,200 bird species.

More than 2500 invasive plants have colonised New Zealand and Australia, which is equivalent to 11% of native plant species, say Kingsford and colleagues.

And many of these invaders have been introduced by government, agriculturalists, horticulturalists and hunters.

Habitat loss

Kingsford and colleagues also point the finger at the threat to biodiversity from habitat loss and degradation.

Australian agriculture had modified or destroyed about 50% of woodland forests and 70% of remaining forests have suffered ecologically from logging, they say.

In all, Kingsford and colleagues identify six major threats to Oceania and say burgeoning populations are set to put further pressure on the area.

Australia is set to increase its population by 35%, New Zealand by 25%, Papua New Guinea by 76% and New Caledonia by 49% by 2050, they say.

"We've already probably got the worst extinction rate of anywhere in the world," says Kingsford. "We're just going to exacerbate that extinction record."

Other threats include the threat of disease, over-exploitation of wildlife and pollution.

Oceans of risk

Kingsford says Oceania is particularly vulnerable to invasive species, because there are so many islands, which did not evolve many predators.

"That's why so many bird species got knocked off when rats, mongooses and possums invaded," he says.

Kingsford and colleagues are particularly concerned about destructive fishery practices, including bottom trawling, in which large areas of ocean floor are "clear felled", and the use of explosives to blow up coral reefs.

Rising seas linked to climate change not only inundate low-lying islands and coastlines, but interacts with other threats in very complex ways, that scientists are still struggling to understand, says Kingsford.

He also says more research is needed in the Pacific as 88.6% of research on key biodiversity threats centre on Australia, New Zealand and Hawaii.